Telephone-exchange system



June 9; 1925.

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C. L. GOODRUM TELEPHONE EXCHANGE SYSTEM Filed July 1, 1920 2Sheets-Sheet 2 Nw O OO OOOOOO @www NN No .ww N omooo Il. m40 RQW@ o o ILQ L OO O o E o@ .U y w QQ ww r `Q Z A C w Q?- /n Verl fof. Char/e5 L.Good/'um Patented .lune 9, 1925.

narran STATES 1541,34? PATENT: oFFlcE.

CHAR-LES L. GOODRUM, OF NEVI YORK, N. Y., ASSIGNOR TO WESTERN ELECTRICCOM.- PANY, INCORPGRATED, OF NEW YORK, N. Y., CORIEORATION OF'NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed .Tuly 1, 1920. Serial No. 393,389.

.7710 all whom. t may concern.

Be it known that l, CHARLEs L. CrooDnUM, a citizen of the United States,residing at New York, in the county of New York, State of New York, haveinvented certain new and useful Improvements inTelephone-Exchange'SysteIns, of which the following is a full, clear,concise, and exact description.

This invention relates to telephone exchange systems and particularly tocircuit arrangements for private branch exchanges employing automaticswitching apparatus, where such exchanges are used in connection withcentral oiiices.

The object of the invention is to provide means whereby a minimum numberof switching means will be employed at the private branch exchange forinterconnecting subscribers thereat and for establishing connectionsover trunk circuits to the central oiiice.

In accordance with the object of the in-` vention each subscribers lineof the private branch exchange is provided with a nonnumeroial switch.Accessible to these switches are a number of connector switches for thepurpose of connecting a calling to a called line. Cn calls to the central otlice, however, a line is lirst extended to a connector switch andupon reaching a pre-determined Contact thereat, a switchingoperation atthe non-numercial switch is caused automatically to take place so that.

the connection with an idle trunk is es tablished independently of theconnector. The connector is thereupon released and is available forestablishing local connections. F or a more complete understanding otthe invention, reference may be had to the following description inconnection with the accompanying drawings in which Fig. l. shows anembodiment of this invention einploying a line finder as a non-numercialswitch and in which Fig. 2 shows an einbodiinent of the inventionemploying` a line switch as the non-numercial switch.

Referring to Fig. 1 of the drawings, there is shown a callingsubscribers station *il 'and a called subscribers station B. Upon theinitiation ot' a call by a subscriber at sub-station A, a line finder Fis set in operation to extend the calling line over a link to aconnector K. Under the control of an impulse sender 5 the subscriber ofsub-station A may set the connector K upon the terminals of any desiredline of Ythe private branch exchange. It, however, the subscriber ofsub-station A desires to extend his line to the .central oilice, he willdial a pre-determined number, whereupon his line will be disconnectedfrom the line tinder F and connected lto an idle finder switchv M forthe purpose of extending his line to the central oliice. Connectorswitch yl andline finder switch F and the inter connecting link willthereupon be vreleased and are availablefor further use.

Referring to Fi 2 of the drawings, a calling subscriber and a calledsubscriber L are shown. In response to the initiation ot Va call, a lineswitch N extends the line of they calling subscriber over a link to anidle connector such as C. The subscriber of station G, may set theconnector C upon the terminals of a desired line such as'L bymanipulating his impulse sender S1. If, however, theV subscriber ofstation Cr desires a direct connection with the central office, he Vwilldial a pre-determined number,

whereupon line switch N will be caused to seek an idle trunk, such VasT, leading to 'the central ollice. Connector C is thereupon released andis available i'or further use.

The apparatus and wiring necessary for testing and ringing a subscribersline have not been shown, since such operations are well known to thoseskilled in the art and are made in a manner similar to that disclosed inPat. No. 1,231,018 of June 26, 1917, to C. L. Goodrum. Y lt is believedthat the operation of this system will best be understood by tracing acall through the various switches. Upon the Vremoval oit the receiverfrom the switch hook at substation A, line relay 110 is energized over apath extending :trom grounded battery, lett hand winding of relay 110,the outer armature and back oontact ot relay 111, through the substationloop, the back contact and inner armature of relay 111 and right handwinding ot relay 110 to ground. Relay 110 in operating v completes acircuit for relay 112 over a cir cuit extending from ground, thearmature and front contact ot relay 110, the inner right hand armatureand back contact of slow to release relay 113', and winding of relay 112to grounded battery. Upon the energization `of relay 112, a circuit forescape magnet 114 is completed over a path extending'from ground, irontcontact and outer armature of relay 112, contacts 120 which are openedupon the iirst movement of the'brusllesand Winding of magnet 114 togrounded battery li/Iag'inet 114 in operating locks up over a path fromgrounded battery, the Winding' of magnet 114, right hand armature andfront .Contact thereof, side switch arm 118 and brush 119,

vcontact 121, to ground at the inner armature and back contact olfagroup relay such 112 ifthe group relay is not energized, and 'providedthat upon the initiation oi: ,this call brush 119 is not resting uponcontact 121` Magnet 114 in operating also comg'iletcs a circuit forprimary Stepping magnet 115, said circuit ,extending from groundedbattery, the ironticontact and left hand armature .of magnet 114,armature and back fontact of stepping ma 'a .et 115' and side switch arm117 to ground. Since the primary stepping` magnet 115 interrupts its owncircuit, itcontinues to ,step as as magnet 114 remains energized. Magnet114 remainsenergized long as brush. 119 which is of t-heloridging typeengages Vidle terminals or terminals upon which ground is present. lWhenthe brush 119 engages `contact A121 no ground will be present thereondue to relay 112 being energized, whereupon magnet 114 rele-ases .itsarmatures thereby opening lthe operating circuit tor stepping magnet115, which ceases stepping. net 114 in retracting its armatures moresside switch arms 117v and 118 into their second positions, 1n position 2ot the side switch arms the secondary stepping magnet 116 is energizedand in attracting its armatures moves the brushes one step intoeugagement with the first set of terminals. Upon the :first .step ot thebrushes .escape magnet 114 is en Vized over a path extending tronigrounded battery, the Winding oi'i magnet 114, outer i'ght bandvarmature and .liront contact o' stepp' magnet 116, the side switch arm118 and -ts second contact, brush `144, to ground at the back contactand -armature olfline relays such as 110 to ground, it' the firstterminal en"aged is not `that ofi the calling line. lr1`he bri hes otthe yrinder switch being oi the bridging type, magnet 114 loclred upthrough its right hand contacts, arm 118, brush 144 and its associatedterminal to ground at the l ontacts ot the line relays and this circuitis not opened until the brushes of rthe linderswitch cen-ter upon theline terminals of the calling line. rrlhe stepping circuit tor secondarymagnet 116 thus maint-ainecL until brushes 1401!.) 144 inclusive ot theline inder switch engage terminals 146 to 150 ir'iclusimeV respectivelyo the calling line. As soon this set ot terminals is'reached the lockingcir for esape magnet 114 will be opened due .to Iline relay 110 beingenergiaed. Es# cape magnet 114 thereupon releases itsy armatures therebymoving side switch arms 11T, 122 and 118 into their third position, thusopening the stepping circuit for secondary magnet 11G. ln position f2or" .the side switch arm 1117, a circuit is completed for cutoff relay'111 over a path extending from grounded battery, the Winding of cutoffrelay 111, terminal 148, brush 142, and side switch arm 117 in its thirdposition to ground ltelay 111 in opera-ting extends the calling linethrough to-line relay 182 fot'k the 'onnw or l and disconnects the linerelay 11() from the calling line. rglhe latter in deenewrizing releasesrelay liinerelay oiY the connector K is .thus energized over pathextending from groundedbattory, the lejt't hand winding oit relay 182,brush 140, terminal 45, through .the substation loop, thebaolr ,Contactand outer lett hand armature ot relay 118, terminal. 147 brush141 andright hand Winding o' relay 182 to ground. Relay 182 in opera ingcompletes a circuit at left hand armature and lront Contact forslow-to-release,relay 183.

The subscriber may non' proceed to send out impulses in accordance withthe number ot' the desired substation. rllhe interruptions or the linecircuitk caused by the Lsubscriber operating the sender S causesimpulses to be sent to the stepping magnet 18,6 of the connector, whichpositions the proper brush below the group or" contracts containing .thedf d line. The circuit for operating stepping magnet 186 may b e Atracedfrom grounde the armature and back contact of relay 1.82, the armatureand front contract of slow to release relay 188, side switch 188 and.is.' contact and the Winding of stepping ur net 186 'to groundedbattery. Upon .the .ist de-energization of line relay 182 in reponse tothe sending of impulses a circuit completed for slou'to-release relayelay 184 in operating `at its outer armature and front contactcomple-tes a circuit for escape magnet 101. Vllhen the line cirfuitbecomes closed upon the termination of the .first set of impulses thesloW-to-release relay 184 dey-energizes due to the opening orn itscircuit at the armature and bacl contact of relay 182. Relay 184 inretracting its armatures opens the circuit 'for escape ,magnet 101 whichupon Cle-energizing moves theside suf'itch arms of connector K intoposition 2. The arm 188` thereupon substitutesthe secondary steppingmagnet 187 in place ot the paint-ry stepping magnet 186 in thesteppingcircuit. The interruptions co 1,responding to the -units digitare vthen sent to operate vthe magnet 187. in the following cirn cuit,grounded battery, Winding of secondary magnet 187 side switch arm 188`and its second Contact, front contactaand armature ot' sloW-to-releaserelay 188, yandYarmature and back contact of relay'182 to ground.` Theslow-to-release relay 183remains energized during the shortinterruptions of .the line relay corresponding to the units digit as inthe operation of sending the tens digit. As before, the slow-to-releaserelay 184 is again energizedupon the rst deenergization of line relay182 and energizes the escape magnet 101. Upon the cessation of theinterruptions of the line circuit corresponding to the units digit, theslow to release relay 184 becomes deenergized thereby opening thecircuit for escape magnet 101 which in deenergizing moves the sideswitch arms into position 3. The brushes 194, 195 and 196 of theconnector switch K are now set upon the terminals 197, 198, and199'respectively of the desired line. A description of the operation anda showing'of the apparatus necessary for testing and ringing the calledsubscriber is not deemed necessary since arrangement shown is applicableto any well known system. Upon the response of the called subscriber theside switch arms 191, 192, 193 and 188 of the connector K are moved intotheir fourth positions in the well known manner.

The calling subscriber is now supplied .with talking battery through thewindings of line relay 182 and the called subscriber through thewindings of relay 185. Upon the termination of the conversation and therestoration of the receiver to the switch hook at substation A, linerelay 182 deenergizes thereby opening the circuit for slow-to-releaserelay 183 which complete circuit 'for release magnet 189 over a pathextending from ground, armature and back Contact of relay 182, armatureand back contact of relay 183, off normal contact 103 (closed upon theprimary movement of the switch brushes), and winding of release magnet189 to grounded battery. Release magnet 189 attracts vits armatures andlocks up through its own contacts thereby restoring connector K tonormal in the well known manner. Upon reaching normal position the offnormal contacts 103 are'again opened and release magnet 189 deenergizes.At the moment the circuit is completed for release magnet 189 of theconnector, a circuit was also completed for release magnet 190 of thelinder switch, said circuit extending from ground, the armature and backcontact of line relay 182, the armature and back contact of slow torelease relay 183, side switch arm 122 and its third contact off normalcontact 102 and winding of release magnet 190 to grounded battery.Release magnet 190 also locks up through its own contacts and causes therestoration of theline inder switch F to normal position. Upon reachingnormal position the off normal contacts 102 are opened and releasemagnet 190 deenergizes.

through to the connector K in the same manner as heretofore describedfor an interconnection with subscriber B'. The subscriber will thenoperate his impulse sender S in accordance with a pre-determined numberwhich, for the purpose of this disclosc ure will be assumed to be No.94. Inresponse to the sending of the impulses corresponding to thesedigits theconnector K willrfirst be removed in a primary direction andthen in a secondary direction as heretofore described for aninterconnection, and the brushes 194, 195 and 196 will be positionedupon terminals 157, 158 and 159 respectively of connector K.

After having sent the second series of impulses, the escape magnet 101will deenergiz'e, due to slow-to-release relay 184 releasing itsarmatures, tl'iereby moving sideI switch arms 191, 192, 193 and 188 intotheir third positions. Inf the third position of arm 193, a circuit iscompleted for relay 113 over a path extending fromground, the sideswitch arm 193 and its third contact, brush 196, terminal 159, brush 143and terminal 149 of line finder F and right hand winding or'slo-w-to-release relay 113. Re-

lay 113 energizes and at theouter left hand armature and back contactthereof, the circuit for line relay 182 of the connector K is opened.lRelay 182 thereupon deenergizes causing in turn the deeuergization ofslow-to-release relay 183. Release magnet. r190 of the line inderF andrelease magnet 189 of the connector K are thereupon `energized overpaths previously traced causing the return of their respective switchesto normal position. 7When switch F returns to normal the circuit forcutoi'lx relay 111 is-opened at the arm 117'. Relay 111 thereupondeenergizes thereby again connecting line'relay `110 to the lcalling`line. Line relay gs again energiz'edand slow-to-release Arelay 113 ismaintained energized over winding of relay v110,'inner armature. andVback Contact of relay y111-through they substation loop, `the backcontact and outer armature of relay 111 andfthence in parallel, oneVpath extending through the left hand winding-'of line relay 110 tobattery, and the other path through the inner left hand armature andfront contact and left hand ,winding of slow-to-release-relay 113 -acircuit extendingfrom ground, right hand to grounded battery, Relay 152is then energized over a path extending from grounded battery, thewinding of relay V152, through-the front contact and inner right handarmature ot relay 113 and the-front contact and armature of relay 110 toground. Relay 152 in energizing completes a circuit for magnet 174 oftinder switch M oven a path extending from ground, liront contact andouter armature ot relay 15,2, contacts ofi'. normal 107, and the Windingof magnet 174 to grounded battery. l/Vagnvet 174 in energizing locksV upover a path similar to that described for magnet 114 ot the line finderF. A circuit is also completed for stepping magnet 175 over a pathextending from ground, arm 1 77 ufinding, hack contact and armature ofmagnet v175 and lett armature and front Contact o1' magnet 17.4 to er.1651 batter Stepping riagaet 17.5 new Continues .t0 Ster the' brushes16:01to 163 inclusive ot line vfinder switcljilfffl or r its associatedcontacts. Whe-n the brush 145 engages Contact 151 no ground will hepresent thereon and magnet'174 Will loe deenergized thereby opening stepVping circuit for stepping magnet 1.75. MagnetV 174 in deenergizinginoyes the side switch arms 177, 123 and 109 into their secondiposition. In position 2 of side switch brushes a circuit is completedYlor secondary ,magnet 176. Magnet 176 in .attracting its armaturesmoves'the brushes `160 to 163 inclusive one step and closes a ,circuitfor magnet 174' overa path eX- tending lfrom grounded battery, Windingmagnet 174, outer armature and loa/cl; ,contact of magnet 176, arm. 109and its second Contact, brush 163, to ground at the puter right handarmature of other relays such as 113'associated with the line vfinderswitch M. Upon energization, magnet 174 locks up through its rightV handVcontacts over this circuit. Under control o1: stepping magnet 17 6, thebrushes of the switch M are moved from terminal to terminal untilterminal 167 is reached. Since relay 113 is energized the Vholdingcincuit for magnet 174 at the outer right hand armature and back Contactof relay 113 is opened which will cause stepping magnet 174 todeenergize. Magnet 174 in deenergizing moves side switch arms 177, 123and-10.9 from their second to'their third positions Due to the openingAof the .circuitforstepping'magnet 176 at the second contact oit sidesxvitch arm 177, said steppingmagnet ceases lstepping. .A circuit isthen completed orcutoltirelay 111 over a path extending fromground,'ar1n 17 7 and Iits third Contact, brush 162, terminal 166, andWinding-"ot cutoil relay 111`to `grounded battery. Relay 111 inattracting its armatures disconnects line relay 110 from the callingline and opens the locking circuit for relay 113. Relay11'3'in'deenergizing extends the calli'ng'line through to`- terminals164 and: 165 of' the line finder switch M. A `circuit is then completedfor4 line relay 180 at the central ottico over a path extending 'fromground, the hack Contact and outer armature of relay 179, conductor136', `lorush 160,

terminal 164, through the substation loop, haci:y contact and zo"uter"le.tv .hand armature otrelay 113, terminal 165, brush 161, con-'ductor 137, 'Tvinding of 1^elay"'-126, inner armature and o ck contactof relay 179 and Winding or' relay in attracting its arnatures completesa circuit for line siffnal 131' thushinldifcating to. 'the operatoratv-the central oliice that a call has arrive-d. Relay 126 isalso'elnergized thereby closingh circuit through its larma ture andfront Contact' ot 'sloyuf to, release rela-y 127. Y i

Theopcrator at the central ofiice noting the lure-'signal may 'insertthe answering plug` 106 ci 4any uell known cord circuit such l), tviortion Vonly et which `'is l own)v into j 1'73 and after having` in- Y-hscrib'er vd suhnner. i Upon 'compleiorf and restoration of the 4. 1the'direct -e substation A, whereupon relay y'll d .-cnergize causing inturn the relay u127. fr circuit is then comrelease magnet 125 ot theline ver a path; extending from ground, fand oar-lr contact ot relay126, arm ture and hack contact oit reay127, side switch arm'123 and itsthird Contact, Vott normal contacts 4133 and Winding,` ot magnet 125 togrounded battery Release magnet 125 energizes and locks lup' through itsown contacts and tlirlough the ott normal contacts 133 and restorestheline Lnder switch M to nornial position. Upon reaching` normalposition contacts 133 are Vopened Whereupr'ni release i agnet 125releases its armati Line rind-.er switch M in r'eturning` to normalopens the holdingcircuit for cutoff relay 111 vglhereijrpon this relayde--energizes and the Upon the removal of the receiver from the switchhoek` at sul'istation G, circuit for line relay 1.0 is :completed over apath cxtending' 'troni grounded lmttery, the winding ot relay 10, hackcontact and outer lett hand arniature ot relay 11,. through thesubstation loop, inner lett hand armature and hack contact of re-ay 1.1to ground. .f the brushes 24 to 28 inclusive of the switch VN areresting` upon the terminals to which a busy connector is connected orupon terminals With which direct trunks to the central slice areassociated, ground will he connected to brush 26 and a circuit for motormagnet'12 Will he completed over a path extending from groundedbattery.rv the Winding, armature and back contact of magnet 12, frontcontact E130 to ground. Relay'lSO and inner right hand armature of linerelay 10 back Contact and right handy armature of relay 11, lefthandarmature and back contact of slow to release relay 13 and brush 26 toground. Cutoff relay 11 is short circuited and will therefore notenergize. Motor magnet 12 in attracting its armature moves the brushes211 to 23 inclusive of line switch M into engagen'ient with the next setof terminals of the line switch. Assuming` that upon the initiation ofthe call" the brushes were resting upon the first set of terminals shownfor switch N and that the next set of terminals are busy, ground will bepresent on contact 9 thereby again completing the circuit for magnet 12over a path extending from grounded battery, the winding, armature andback contact of magnet 12, the front contact and inner right handarmature of line relay 10, back Contact and right hand armature ofcutoff relay 11, left hand armature and back contact of relay 13, brush26 and terminal 9 to ground. Motor magnet 12 will again tlc-energize andstep the brushes of the switch M into engagen'ient with the next set ofterminals. Assuming that the next set of terminals to which theconnector C is connected are idle, no ground will be present upony thetest terminal 22 andmotor magnet 12 will therefor not be energized. Acircuit will, however, be completed for cutoff relay 11 over a pathextending from ground, the front contact and left hand armature of relay10,l the winding of cutotf relay 1-, baci/r contact armature and windingof motor magnet 12 to grounded battery. Motor magnet 12 is marginal andwill not operate in series with relay 11. Cutoff relay 11 in energizingdisconnects line relay 10 from the calling line and extends the callingline through to the connector C. Line' relay 30 of the connector isthenenergized over a path extending from ground, the left hand winding ofrelay30, terminal 20, brush 24, front Contact and outer left handarmature of relay 11, through the substation loop, 'the inner left handarmature and front contact of relay 11,` brush 25, terminal 21 and righthand winding'of relay 30 to grounded battery." Relay 30 in operating, atits right hand armaturey and front 'contact completea circuit for slowto release relay 31 'and relay 31 yin operating places ground uponterminal 22 to render the connector C busy and to hold relay 11energized when line relay 10 releases. Belay'31 in attracting its righthand armature prepares a circuit forI slow release relay 34, which inturn when energized completesv a circuit at its outer armature andfrontContact for e'scape magnet 30.

The subscriber'rmay nowl proceed to send out impulses in accordance'with the number ofthe Ldesired line whereupon the' brushes staal' and e2will be set upon the terminals ills 44;, and l5 of the called line in amanner similar to that heretofore described.

As heretofore stated, the testing and ringing operations are well knownand it is not deemed necessary to complicate the drawing and thedescriptive matter by describing sach operations.

Assuming that the subscriber at substation Cr desires a directconnection with the central oilice, he will after removing` the receiverfrom the switch hook dial the predetermined number which for the purposeof this description will be assumed to be 94. in response to the removalof the receiver from its switch hook line switch lvl will be caused toseek an idle connector as heretofore described, and in response to thesending of the impulses the brushes 40, 41 and 42 will be moved intoengagement with terminals 90, 91 and 92 of the terminal bank ofconnector switch C. After the sending of the second set of impulses sideswitch arm 50 will be moved into its third position due to magnet SOreleasing, whereupon a circuit for relay 13 will. be completed over apath extending from ground, arm 50 in its third position, brush e2,terminal 92, conductor 95, terminal 23, brush 27, the left hand windingof slow to release relay 13 and outer hand armature and back contact ofrelay 10 to grounded battery. Relay 13 attracts its armatures and locksup over a path extending' from grounded battery, `the right hand windingof relay 13, right hand armature and front contact thereof, brush 23,and terminal to ground. Relay 13 in energizing opens th'e holdingcircuit for cutolf relay 11 at the left hand armature and back contactof relay 13. Cutoff relay l1 thereupon de-energizes whereupon thecircuit for line relay 10 is again completed. Relay 10 in attracting itsarmature again completes a circuit for motor magnet 12 over aA pathextending from grounded battery, the winding, armature and l ack contactof-motor magnet 12, front contact and inner right hand armature of relay10,v back contact and right hand armature of cutoff relay 11, left handarmature and front contact of relay 13, brush 28 and terminal 70 toground. Under the'control of stepping magnet 12, the brushes 24 to 28inclusive of line switch 10 are moved step by step over the terminals ofsuch switch until the first idle trunk leading to the central oiiice isfound. Assuming that terminal 29 is the first idle trunk leadking to thecentral oice, no ground will be VMotor magnet 12 will present thereon.

Cutoff relay 11 therefore cease stepping.

will then be energized overa path extendy ing from grounded battery, thewinding, armature and back Contact of motor magnet 12, the winding'of'cu'toff'relay v11, vleft hand armature and front Contact of linerelay 10 tog'roun'd. Cutoff relay 11 in attracting its armaturesdisconnects line relay lO from the calling line and extends the callingline through to the trunk conductors l and 2 leading`r to the centraloltice, Relays and (lL/l of the trunk circuit are thereupon energizedover a path extending from groui'id, the back ContactA and outerarmature of relay 65, conductor il terminalO, brush 'rE/l1 Contact andouter left. hand armature ol' cutoll relay ll, through the substationloop, the inner left hand: armature and iront Contact oil relay il,brush terminal Gl, winding of relay 62, conductor f, inner armature andback Contact ot'ieiay G5, and winding of relay (il to grounded battery.Relay G52 in ene 'zing completes a; cir 't for slow to relcae relay @itSlow to rclease relay GP5V in energizing placesrgronnd upon terminal Q9iter maintaining relay 13 in a locked conditiond Linear-clay Gl', at thecentral oliceiin energizing, completes acir cuit for line signal 67 thusindicating to the operator thereat. that a call has arrived.

The operator noting the line signal GT vwill insert the answering end ofcord vircuit (a portion only ot which is l"o\vn) into jack 6G, whereuponrelay (55 wh be energized thus disconnecting relay Gel trom the trunkconductors l and 2. Relay (Se in deenergizingiopens the circuit for linesiin'ial 67. Battery gtorho'ldingj relay 62 ener iced and tor' talkingis now supplied throi" jh the windings of repeatingl coil After having;inquired the wants of the calling subscriber Vthe operator may completetheI connection in the welLlrnO-:n manners Upon completion ot theconversation and the restoration of the receiver to the switchhoolat-substation G, relay GS will be de energized due to the opening ofthe direct current path over the trunk conductors l and 2. Relay 62 inreleasing opens a ci'rcuit for relay 63v whichY in releasing removesground rom'terminal 29 of the line switch. Upon the removal otthisground relay 13 cle-energizes, which in turn releases cutoff relay 1l.Thesystem is thenready for the next call. Y c

While the invention has been shown in connectionwith trunks extending toa man'- ual exchange, it will be understood that: it is equally wellsadaptable for use' in a system in which the trunks extend to anautomatic exchange.

What is claimed is: y i

In a telephone systenntelephone lines, trunk lines, a link ci'rt'mit,VVVsubscriber controlled means for including saidlink circuit in'connection between said 1 telephone lines and'pme'ans positivelycontrolledby the sub"- scrlbfer for excluding saidfl-inl; circuit from aconnection between a telephone-.line and a trunlrlinef Y v 2.' atelephone system, telephone lines, trunk lines, a series of automaticswitches Yphone line and a trunk line.

including a non-numerical switch, subscriber controlled means forincluding said automatic switches in a connection between a calling anda called line, and means positivelj)r controlled by the subscriber torex- 'Y cluding all switches except said nonnumeri-V cal switch tromaconnection between a tele- 3. ln telephone system, a. calling andacalled line, a trunk line, a non-numerical switch and a numericalswitch, subscriber controlled means for operating` said switches tointerconnect said calling and called lines, and means responsive to apredetern'iined setting ol said numerical switch torreleasing saidnumericalswitch and for establishing a connection betweenv said callingYline and said trunlr line through said non-numerical switchindependently of said 'numerical switch.

l. ln a telephone system, a callingI line, a called line, a trunk line,a non-numerical and a numerical switch, an iin-pulse senderv for saidcalling line, means responsivev to the initiation ot'a call Vand thcactuation ot said sender for interconnecting saidwcalling'and calledlines over a circuitincluding said nonnumerical switchV and saidfnumerical switch, and means responsive to the initiation et a call andapredetermined actuation of said sender for releasing said numericalswitch and tor interconnectingsaid calling lineand said trunk line overa circuit including said non-uumerical switch only.

5. In a telephone system, subscribers lines, iirst and second switchingmeans, an impulse sender for opera-ting saidt second switching` means tointerconnect iafcalling and-a called line, trunk lines, andy meansactuated upon the sending of a predetermined numberV ot impulsesforreleasing said second switching means and for causing said firstswitchin means to interconnect said callingV line and an idle trunkline'.

6. In a' telephone system, subscribers lines, first and second switchingmeans. an impulse sender fon operating said switching meansto'interconnect a" calling and a calledV line, trunk lines; and meansactuated upon the sendingot a predetermined number of 'mr pulses forcausing said'firstsw-itching' means to become disconnected fromI saidsecond switching means and to interconnect said calling lineY andan'idle trunk linethrough said rst switching means to the exclusion ofsaid second switchingmeans.

7. In a telephone system, subscribers lines, an automatically operatingswitching mechanism,n a directively controlled switching mechanism,means responsive to the initiation `of a call from a calling line tocause' said automa'tically7 operating switching mechanism to entendVsaid calling line to" said dir'ectively controlledk switching mechanism,anrimfpulse fsender for said calling. line to set' said dilos ilo

las

iso

rectively controlled switching mechanism upon the terminals of thecalled line, trunk lines, and means responsive to the initiation of acall and the sending of a predetermined number of impulses to cause therelease of said directively controlled switching mechanism and tofurther operate said automatically operating switching mechanism toextend said calling line to an idle trunk line.

8. In a telephone system, calling lines and called lines, impulsesenders therefor, trunk lines, automatic switches comprising a lineswitch and a connector switch, means responsive to the initiation of acall and the actuation of the impulse sender of acalling line forextending the calling line through a line switch and the connectorswitch to the terminals of a called line, and means responsive to theinitiation of a call and the sending of a predetermined number ofimpulses Jfrom the impulse sender for releasing` said connector switchand for interconnecting the calling line and an idle trunk line throughthe line switch and independently of the connector switch.

9. In a telephone system, a calling line and a called line, impulsesenders therefor, trunk lines, automatic switches including a lineswitch and a connector switch, means responsive to the initiation of acall and the actuation of said impulse sender for interconnecting saidcalling` and called lines through said line switch and said connectorswitch, and means responsive to the initiation of a call and the sendingof a predetermined number of impulses for causing a furtheroperationotsaid line switch to connect the calling line to an idle trunkline and for releasing said connector switch.

l0. In a telephone system, telephone lines,

trunk lines, a link circuit, means including scriber controlled meansincluding said link circuit for selecting an idle trunk circuit andconnecting it directly to a calling line, and means responsive to saidlast means for rendering said link circuit available for use in otherconnections.-

12. In a telephone system, telephone lines, trunk lines, a link circuit,means for manipulating said link circuit to select a telephone line andinclude itself in such connection, means for manipulating said linkcircuit to select a trunk line and exclude itself from such connection,and means responsive to said last means for rendering said link circuitavailable for use in other connections.

In witness whereof, I hereunto subscribe my name this 28th day of June AD., 1920.

CHARLES L. GooDRUM.

DISCLAIMER.

1,541,347.-0har2es L. Goodmm, New York, N. Y. TELEPHONE-EXCHANGE SYS-TEM. Patent dated June 9, 1925. Disclaimer filed April 7, 1928, by theassignee, Western E lect/fic Company, Incorporated.

Hereby enters this disclaimer to the said claim of said Letters Patentwhich is in the following Words to Wit:

12. In a telephone system, telephone lines, trunk lines, a link circuit,means for manipulating said link circuit to select a telephone line andinclude itself in sucli connection, means for manipulating said linkCircuitto select a trunk line and exclude itself from such connection,and means responsive to said last means for rendering said link circuitavailable for use in other connections.

